3951

3951 ALLEGRO

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29319.4† ABSOLUTE MAXIMUM RATINGS Output Current, IOUT Logic Input Voltage Range, Package Power Dissipation, Operating Temperature Range, Storage Temperature Range, Output current rating may be limited by duty cycle, ambient temperature, heat sinking and/or forced cooling. Under any set of conditions, do not exceed the specified current rating or a junction temperature of +150°C. * Fault conditions that produce excessive junction temperature will activate device thermal shutdown circuitry. These conditions can be tolerated but should be avoided. A3951SB 8 9 GROUND GROUND GROUND LOGIC SUPPLY PHASE GROUND GROUND RC SENSE LOAD SUPPLY Dwg. PP-056-1 REF/ LOAD SUPPLY VCC OUTB OUTA VBB VBB LOGIC ENABLE BRAKE NC Designed for bidirectional pulse-width modulated current control of inductive loads, the A3951SB and A3951SW are capable of continuous output currents to ±2 A and operating voltages to 50 V. Internal fixed off-time PWM current-control circuitry can be used to regulate the maximum load current to a desired value. The peak load current limit is set by the user’s selection of an input reference voltage and external sensing resistor. The fixed off-time pulse duration is set by a user- selected external RC timing network. Internal circuit protection includes thermal shutdown with hysteresis, transient suppression diodes, and crossover-current protection. Special power-up sequencing is not required. The A3951SB and A3951SW are improved replacements for the UDN2953B and UDN2954W, respectively. For new system de- signs, the A3952SB/SEB/SLB/SW are recommended. With the ENABLE input held low, the PHASE input controls load current polarity by selecting the appropriate source and sink driver pair. A user-selectable blanking window prevents false triggering of the PWM current control circuitry. With the ENABLE input held high, all output drivers are disabled. When a logic low is applied to the BRAKE input, the braking function is enabled. This overrides ENABLE and PHASE to turn off both source drivers and turn on both sink drivers. The brake function can be safely used to dynamically brake brush dc motors. The A3951SB is supplied in a 16-pin dual in-line plastic package with copper heat-sink contact tabs. The lead configuration enables easy attachment of a heat sink while fitting a standard printed wiring board layout. The A3951SW, for higher package power dissipation requirements, is supplied in a 12-pin single in-line power-tab package. In either package style, the batwing/power tab is at ground potential and needs no isolation.

FEATURES

I ±2 A Continuous Output Current Rating I 50 V Output Voltage Rating I Internal PWM Current Control I Internal Transient Suppression Diodes I Under-Voltage Lockout I Internal Thermal Shutdown Circuitry I Crossover-Current Protection I Default Brake Current Limit Always order by complete part number: Part Number Package R θJA RθJT A3951SB 16-Pin DIP 43 °C/W 6.0 °C/W A3951SW 12-Pin Power-Tab SIP 36 °C/W 2.0 °C/W FULL-BRIDGE PWM MOTOR DRIVER

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-50002 VBB RC LOAD SUPPLY PHASE UVLO & TSD RS Dwg. FP-036-1 REF/ OUTA OUTB ENABLE SENSE– BRAKE R INPUT LOGIC GROUND Q R S

1.5 V PWM LATCHVCC + –

TEMPERATURE IN °C Dwg. GP-032A SUFFIX 'B', R = 43°C/WθJA SUFFIX 'W', R = 38°C/WθJA SUFFIX 'W', R = 2.0°C/WθJT SUFFIX 'B', R = 6.0°C/WθJT ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS TRUTH TABLE BRAKE ENABLE PHASE OUT A OUTB DESCRIPTION H H X Z Z Outputs Disabled H L H H L Forward H L L L H Reverse L X X L L Brake, See Note X = Irrelevant Z = High Impedance (source and sink both off) NOTE: Includes internal default Vsense level for over-current protection. Copyright © 1994, 2000 Allegro MicroSystems, Inc. FUNCTIONAL BLOCK DIAGRAM

3www.allegromicro.com 1 2 3 4 5 6 7 8 9 10 11 12 GROUND Dwg. PP-058-1 LOGIC SUPPLY PHASE RC SENSE REF/ LOAD SUPPLY OUTB OUTA ENABLE VCC VBB LOGIC BRAKE LOAD SUPPLY NC Continued next page … A3951SW ELECTRICAL CHARACTERISTICS at TA = +25°C, VBB = 50 V, VCC = 5.0 V, VREF = 2.0 V, VSENSE = 0 V, RC = 20 kΩ/1000 pF to Ground (unless noted otherwise). Limits Characteristic Symbol Test Conditions Min. Typ. Max. Units Output Drivers Load Supply Voltage Range V BB Operating, IOUT = ±2.0 A, L = 3 mH V CC – 50 V Output Leakage Current I CEX VOUT = VBB – <1.0 50 µA VOUT = 0 V – <-1.0 -50 µA Output Saturation Voltage V CE(SAT) Source driver, IOUT = -0.5 A – 0.9 1.2 V Source driver, IOUT = -1.0 A – 1.0 1.4 V Source driver, IOUT = -2.0 A – 1.2 1.8 V Sink driver, IOUT = +0.5 A – 0.9 1.2 V Sink driver, IOUT = +1.0 A – 1.0 1.4 V Sink driver, IOUT = +2.0 A – 1.3 1.8 V Clamp Diode Forward Voltage V F IF = 0.5 A – 1.0 1.4 V (Source or Sink) I F = 1.0 A – 1.1 1.6 V IF = 2.0 A – 1.4 2.0 V Load Supply Current I BB(ON) VENABLE = 0.8 V, VREF = 2.0 V – 2.9 6.0 mA (No Load) I BB(OFF) VENABLE = VREF = 2.0 V – 3.1 6.5 mA IBB(BRAKE) VBRAKE = 0.8 V – 3.1 6.5 mA

Worcester, Massachusetts 01615-0036 (508) 853-50004 Control Logic Logic Supply Voltage Range V CC Operating 4.5 5.0 5.5 V Logic Input Voltage V IN(1) 2.0 –– V VIN(0) –– 0.8 V Logic Input Current I IN(1) VIN = 2.0 V – <1.0 20 µA IIN(0) VIN = 0.8 V – <-2.0 -200 µA Reference Voltage Range V REF Operating 2.0 – VCC V Reference Input Current I REF 2.0 V ≤ VREF ≤ VCC 25 40 55 µA Reference Voltage Divider Ratio – VREF = 5 V 9.5 10.0 10.5 – PWM RC Fixed Off Time t off CT = 1000 pF, RT = 20 kΩ 18 20 22 µs PWM Minimum On Time t on(min) CT = 820 pF, RT ≥ 12 kΩ – 1.7 3.0 µs CT = 1200 pF, RT ≥ 12 kΩ – 2.5 3.8 µs Propagation Delay Time t pd IOUT = ±2.0 A, 50% EIN to 90% EOUT transition: ENABLE on to source driver on – 2.9 – µs ENABLE off to source driver off – 0.7 – µs ENABLE on to sink driver on – 2.4 – µs ENABLE off to sink driver off – 0.7 – µs PHASE change to source driver on – 2.9 – µs PHASE change to source driver off – 0.7 – µs PHASE change to sink driver on – 2.4 – µs PHASE change to sink driver off – 0.7 – µs tpd(pwm) Comparator trip to sink driver off – 0.8 1.5 µs Thermal Shutdown Temperature T J – 165 – °C Thermal Shutdown Hysteresis ∆TJ – 15 – °C UVLO Disable Threshold V CC(UVLO) 3.15 3.50 3.85 V UVLO Hysteresis ∆VCC(UVLO) 300 400 500 mV Logic Supply Current I CC(ON) VENABLE = 0.8 V, VREF = 2.0 V – 20 30 mA (No Load) I CC(OFF) VENABLE = VREF = 2.0 V – 12 18 mA ICC(BRAKE) VREF = 0.8 V – 26 40 mA NOTES: 1. Typical Data is for design information only. 2. Each driver is tested separately. 3. Negative current is defined as coming out of (sourcing) the specified device terminal. Limits Characteristic Symbol Test Conditions Min. Typ. Max. Units ELECTRICAL CHARACTERISTICS (Continued)

Worcester, Massachusetts 01615-0036 (508) 853-50006 Choosing a small value for RS essentially disables the current limiting during braking. Therefore, care should be taken to ensure that the motor’s current does not exceed the absolute maximum ratings of the device. The braking current can be measured by using an oscilloscope with a current probe connected to one of the motor’s leads. CAUTION: Because the kinetic energy stored in the motor and load inertia is being converted into current, which charges the V BB supply bulk capacitance (power supply output and decoupling capacitance), care must be taken to ensure the capacitance is sufficient to absorb the energy without exceeding the voltage rating of any devices connected to the motor supply. RC Fixed Off Time The internal PWM current control circuitry uses a one shot to control the time the driver remains off. The one shot time, t off (fixed off time), is determined by the selection of an external resistor (RT) and capacitor (CT) connected in parallel from the RC terminal to ground. The fixed off time, over a range of values of C T = 820 pF to 1500 pF and RT = 12 kΩ to 100 kΩ, is approximated by toff = RT•CT. When the PWM latch is reset by the current compara- tor, the voltage on the RC terminal will begin to decay from approximately 3 volts. When the voltage on the RC terminal reaches approximately 1.1 volts, the PWM latch is set, thereby re-enabling the driver. RC Blanking In addition to determining the fixed off time of the PWM control circuit, the C T component sets the compara- tor blanking time. This function blanks the output of the comparator when the outputs are switched by the internal current control circuitry (or by the PHASE, BRAKE, or ENABLE inputs). The comparator output is blanked to prevent false over-current detections due to reverse recovery currents of the clamp diodes, and/or switching transients related to distributed capacitance in the load. During internal PWM operation, at the end of the off time, the comparator’s output is blanked and C T begins to be charged from approximately 1.1 V by an internal current source of approximately 1 mA. The comparator output remains blanked until the voltage on C T reaches approxi- mately 3.0 volts. Similarly, when a transition of the PHASE input occurs, CT is discharged to near ground during the crossover delay time (the crossover delay time is present to prevent simultaneous conduction of the source and sink drivers). After the crossover delay, C T is charged by an internal current source of approximately 1 mA. The comparator output remains blanked until the voltage on C T reaches approximately 3.0 volts. Similarly, when the device is disabled via the ENABLE input, CT is discharged to near ground. When the device is re-enabled, CT is charged by the internal current source. The comparator output remains blanked until the voltage on C T reaches approximately 3.0 V. For most applications, the minimum recommended value is CT = 820 pF ±5 %. This value ensures that the blanking time is sufficient to avoid false trips of the com- parator under normal operating conditions. For optimal regulation of the load current, the above value for C T is recommended and the value of RT can be sized to deter- mine toff. For more information regarding load current regulation, see below. LOAD CURRENT REGULATION WITH THE INTERNAL PWM CURRENT-CONTROL CIRCUITRY During operation, the A3951S– have a lower limit to the range of PWM current control. This directly relates to the limitations imposed by the V REF input (2.0 V, minimum). Applications requiring a broader or full range (≈0% to 100%) should utilize the A3952S–, which are recom- mended for the improvements they bring to new designs. LOAD CURRENT REGULATION WITH EXTERNAL PWM OF THE PHASE OR ENABLE INPUTS The PHASE or ENABLE inputs can be pulse-width modulated to regulate load current. Typical propagation delays from the PHASE and ENABLE inputs to transitions of the power outputs are specified in the electrical charac- teristics table. If the normal PWM current control is used, then the comparator blanking function is active during phase and enable transitions. This eliminates false tripping of the over-current comparator caused by switch- ing transients (see “RC Blanking” above).

Worcester, Massachusetts 01615-0036 (508) 853-50008 To minimize current-sensing inaccuracies caused by ground trace I•R drops, the current-sensing resistor should have a separate return to the ground terminal of the device. For low-value sense resistors, the I•R drops in the PCB can be significant and should be taken into account. The use of sockets should be avoided as contact resis- tance can cause variations in the effective value of R Larger values of RS reduce the aforementioned effects but can result in excessive heating and power loss in the sense resistor. The selected value of R S must not result in the SENSE terminal absolute maximum voltage rating being exceeded. The recommended value of R S is in the range of RS = (0.375 to 1.125)/ITRIP. Thermal Considerations For the most reliable operation, it is recommended that the maximum junction temperature be kept as low as practical, preferably below 125°C. The junction tempera- ture can be measured by attaching a thermocouple to the power tab/batwing of the device and measuring the tab temperature, T T. The junction temperature then can be approximated as TJ ≈ TT + (2 • VF • IOUT • RΘJT) where VF is the clamp diode forward voltage and can be determined from the electrical specification table for the given level of I OUT. The value for RΘJT is given in the package thermal resistance table for the appropriate package. The power dissipation of the batwing package can be improved by approximately 20% by adding a section of printed circuit board copper (typically 6 to 18 square centimeters) connected to the batwing terminals of the device. The thermal performance in applications with high load currents and/or high duty cycles can be improved by adding external diodes in parallel with the internal diodes. In internal PWM applications, only the two top-side (flyback) diodes need be added. For external PHASE or ENABLE input PWM applications, four external diodes should be added for maximum junction temperature reduction. PCB Layout The load supply terminal, V BB, should be decoupled (>47 µF electrolytic and 0.1 µF ceramic capacitors are recommended) as close to the device as is physically practical. To minimize the effect of system ground I•R drops on the logic and reference input signals, the system ground should have a low-resistance return to the load supply voltage. See also “Current Sensing” and “Thermal Consider- ations” above. Fixed Off-Time Selection With increasing values of t off, switching losses de- crease, low-level load-current regulation improves, EMI is reduced, the PWM frequency will decrease, and ripple current will increase. The value of t off can be chosen for optimization of these parameters. For applications where audible noise is a concern, typical values of t off are chosen to be in the range of 15 to 35 µs. DC Motor Applications In closed-loop systems, the speed of a dc motor can be controlled by PWM of the PHASE or ENABLE inputs, or by varying the REF input voltage (V REF). In digital systems (microprocessor controlled), PWM of the PHASE or ENABLE input is used typically thus avoiding the need to generate a variable analog voltage reference. In this case, a dc voltage on the REF input is used typically to limit the maximum load current. In dc servo applications that require accurate position- ing at low or zero speed, PWM of the PHASE input is selected typically. This simplifies the servo-control loop because the transfer function between the duty cycle on the PHASE input and the average voltage applied to the motor is more linear than in the case of ENABLE PWM control (which produces a discontinuous current at low- current levels). With bidirectional dc servo motors, the PHASE termi- nal can be used for mechanical direction control. Similar to when braking the motor dynamically, abrupt changes in the direction of a rotating motor produce a current gener- ated by the back EMF. The current generated will depend on the mode of operation. If the internal two-quadrant slow-decay PWM current-control circuitry is used, the maximum load current generated can be approximated by I LOAD = VBEMF/RLOAD where VBEMF is proportional to the motor’s speed. If external four-quadrant fast-decay ENABLE PWM current-control is used, then the maximum load current generated can be approximated by I LOAD = (VBEMF + VBB)/RLOAD

9www.allegromicro.com Typical Bipolar Stepper Motor Application For both cases, care must be taken to ensure that the maximum current ratings of the device are not exceeded. The load current will limit at a value ILOAD = VREF/(10•RS). CAUTION: When the direction of the motor is changed abruptly, the kinetic energy stored in the motor and load inertia will be converted into current that charges the V BB supply bulk capacitance (power supply output and decoupling capacitance). Care must be taken to ensure the capacitance is sufficient to absorb the energy without exceeding the voltage rating of any devices connected to the motor supply. See also, the section on brake operation under “Functional Description”, above. Stepper Motor Applications The A3951SB and A3951SW may be used for bidrectional control of bipolar stepper motors with continu- ous output currents to 2 A and peak start-up currents as high as 3.5 A. Typical DC Servo Motor Application 25 kΩ 820 pF 0.5 Ω VBB Dwg. EP-048-1 ENABLE2 PHASE2 VREF2 ENABLE1 PHASE1 VREF1 47 µF +5 V 0.5 Ω 25 kΩ 820 pF 1 2 3 4 5 6 7 8 9 10 11 12 VCC VBB LOGIC 123456789101112 VCC VBB LOGIC 47 µF 8 9 VCC VBB VBB LOGIC Dwg. EP-047-1 0.5 Ω VBB PHASE ENABLE BRAKE +5 V 25 kΩ 820 pF

Worcester, Massachusetts 01615-0036 (508) 853-500010 A3951SB Dimensions in Inches (controlling dimensions) Dimensions in Millimeters (for reference only) NOTES: 1. Leads 1, 8, 9, and 16 may be half leads at vendor’s option. 2. Lead thickness is measured at seating plane or below. 3. Lead spacing tolerance is non-cumulative. 4. Webbed lead frame. Leads indicated are internally one piece. 5. Exact body and lead configuration at vendor’s option within limits shown. 0.020 0.008 0.300 BSC Dwg. MA-001-17A in 0.430 MAX 1 8 0.280 0.240 0.210 MAX 0.070 0.045 0.015 MIN 0.022 0.014 0.100 BSC 0.005 MIN 0.150 0.115 0.775 0.735 NOTE 4 0.508 0.204 7.62 BSC Dwg. MA-001-17A mm 10.92 MAX 1 8 7.11 6.10 5.33 MAX 1.77 1.15 0.39 MIN 0.558 0.356 2.54 BSC 0.13 MIN 3.81 2.93 19.68 18.67 NOTE 4

11www.allegromicro.com NOTES: 1. Lead thickness is measured at seating plane or below. 2. Lead spacing tolerance is non-cumulative. 3. Exact body and lead configuration at vendor’s option within limits shown. 4. Lead gauge plane is 0.030” (0.762 mm) below seating plane. A3951SW Dimensions in Inches (controlling dimensions) Dwg. MP-007 mm 32.00 31.49 19.69 19.45 0.51 3.94 3.68 ø 4.57 MAX 1.40 1.14 3.43 2.54

7.36 MIN

2.03 1.77 9.27 2.54 ±0.254 0.76 0.51 1.65 0.89 1 0.59 0.45 3.56 14.48 13.71 6.22 5.71 INDEX AREA Dwg. MP-007 in 1.260 1.240 0.775 0.765 0.020 0.155 0.145 ø 0.180 MAX 0.055 0.045 0.135 0.100

0.290 MIN

0.080 0.070 0.365 0.100 ±0.010 0.030 0.020 0.065 0.035 1 0.023 0.018 0.140 0.570 0.540 0.245 0.225 INDEX AREA Dimensions in Millimeters (for reference only)

Worcester, Massachusetts 01615-0036 (508) 853-500012 The products described here are manufactured under one or more Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro products are not authorized for use as critical components in life-support devices or systems without express written approval. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsi- bility for its use; nor for any infringement of patents or other rights of third parties which may result from its use.